How to check storage on a Mac, and what each category means

Check storage in System Settings

On macOS 15 Sequoia, macOS 26 Tahoe and macOS 27 the steps are the same (Apple, See used and available storage space on your Mac):

1. Choose Apple menu › System Settings, then click General in the sidebar.
2. Click Storage. The bar at the top fills in by category. Move the pointer over a color to see what it is and how much it uses; the light gray part at the end is free space.
3. Give it a minute. macOS measures in the background, and the categories, System Data in particular, change size while it works.
4. Click All Volumes to see used and available space for each volume on your internal disk.

The same page is one click away from System Settings › General › About, which has a Storage Settings button (Apple, View About settings).

Under the bar, most categories have an ⓘ button. It opens a list of that category's files that you can sort by Name, Kind, Last Accessed or Size (Apple, Find and delete files on your Mac). For Documents there are extra views for large files and downloads, and a File Browser that shows how much each folder uses.

Quicker ways: Finder and Disk Utility

When you only want the number of gigabytes free, there are faster places to look (Apple, Get file, folder and disk information on Mac):

• Finder's status bar. Open any Finder window and choose View › Show Status Bar. The bar at the bottom shows how many items are in the folder and how much space is available on that disk.
• Get Info on the disk. Select Macintosh HD (or your startup disk's name) in the Finder sidebar under Locations, then choose File › Get Info. Its General section shows the disk's capacity and how much is available and used. If the disk isn't in the sidebar, turn it on in Finder › Settings › Sidebar.
• Disk Utility. Open it from Applications › Utilities. Select a volume to see how much it uses, how much the other volumes in the same container use, and how much is free.

Check storage in Terminal

Two commands give you the raw numbers. Both only read; they change nothing and don't need sudo.

df -H /System/Volumes/Data
diskutil info / | grep -E "Container (Total|Free) Space"

On our MacBook Pro (M2 Max, macOS 27.0.1), the first one printed this, trimmed:

Filesystem      Size    Used   Avail Capacity  Mounted on
/dev/disk3s5    494G    440G     10G    98%    /System/Volumes/Data

and the second reported a container total of 494.4 GB with 10.5 GB free. A few things to read from that:

• Use the Data volume. Your files, apps and settings live on /System/Volumes/Data. Running df on / instead shows the sealed macOS system volume, which reported only about 14 GB used on the same Mac. The two volumes share one pool of free space, so both show the same amount available.
• -H versus -h. df -H counts in powers of 1,000, the way System Settings and Finder do. df -h counts in powers of 1,024 (its man page calls them gibibytes), so the same free space showed as 9.7Gi. Apple explains the two ways of counting in How storage capacity is measured on Apple devices.
• Terminal leaves out purgeable space. df and diskutil report what's free right now. System Settings and Finder also count space macOS can clear on its own, which is why their "available" figure is often higher.

Why the numbers don't match

If Finder, System Settings, Disk Utility and a disk analyzer app each show a different amount free, that's normal. Here are the usual reasons in short; the purgeable space guide compares the figures side by side.

• Purgeable space. Time Machine local snapshots, some caches and copies of files that are already safe in iCloud are counted as available by macOS, because it removes them when space is needed. Tools that count only free blocks don't include them. What purgeable space is, and why it doesn't always free up.
• Units. A tool that counts in GiB, as df -h does, shows about 7% less for the same space.
• Timing. Storage settings measures in the background and can lag behind what you just deleted. The Trash also counts as used until you empty it.
• What each tool can see. An app without permission to read some folders, or one that only scans your home folder, adds up less than the whole disk. Disk analyzer apps, compared.

What each storage category means

Apple's descriptions, from Change Storage settings on Mac, with where to go to shrink each one. You'll only see the categories that apply to your Mac.

Other Users & Shared needs a review of the relevant accounts and shared material; System Data is a separate category that can include temporary files.

When your disk is almost full

When the startup disk runs low, macOS warns you, and saving files or installing updates can fail. It also leaves less room for swap, which is one reason a Mac shows "Your system has run out of application memory". Before reaching for a clean-up app, work through the categories above in this order, because it frees the most with the least risk:

1. Empty the Trash. Nothing you've moved there frees space until you do.
2. Old installers and disk images in Downloads. Once an app is installed, its .dmg or .pkg isn't needed.
3. Large files from the Documents view, sorted by size.
4. iOS Files, if old device backups are there.
5. Apps you don't use, sorted by size in Applications.

The full order, with what you can undo at each step, is in how to free up space on your Mac, safely. If you need space urgently to install a macOS update, Apple notes that starting up in safe mode clears some system caches temporarily (Apple, Free up storage space on Mac).

How Tend helps

Tend's Clean Up page and Space Map show what's large inside your home folder, including app caches, logs, developer files and old installers, and its Files tab finds large and old files, duplicates, similar photos and what cloud folders keep downloaded. Looking is free and changes nothing. With Tend Pro, what you select moves to the macOS Trash rather than being deleted. Tend doesn't measure other user accounts or macOS's own volumes, so Storage settings is still the place for the whole-disk picture. How the storage view works.

Questions

Related guides

Sources

• Apple, See used and available storage space on your Mac
• Apple, Change Storage settings on Mac
• Apple, Find and delete files on your Mac
• Apple, Get file, folder and disk information on Mac
• Apple, View About settings on Mac
• Apple, Free up storage space on Mac
• Apple, How storage capacity is measured on Apple devices
• The df and diskutil man pages on macOS 27.0.1 (man df, man diskutil)

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